Laminated separator for nonaqueous electrolyte secondary battery

Abstract

The present disclosure provides a laminated separator for a nonaqueous electrolyte secondary battery which makes it possible to obtain a battery having an excellent rate characteristic and which has excellent heat resistance, the laminated separator including a polyolefin-based substrate, a heat-resistant layer that is provided on one surface or both surfaces of the polyolefin-based substrate, and a particle layer which is provided on at least one side of the laminated separator, a standard deviation of an IR peak intensity ratio (peak intensity which is of a resin contained in the particle layer and which is in an infrared absorption spectrum/peak intensity which is of a resin contained in the heat-resistant layer and which is in an infrared absorption spectrum) on a surface of the laminated separator which surface is located on the at least one side on which the particle layer is provided being not more than 0.025.

1 . A laminated separator which is for a nonaqueous electrolyte secondary battery and which includes a polyolefin-based substrate and a heat-resistant layer that is provided on one surface or both surfaces of the polyolefin-based substrate,
 the laminated separator comprising a particle layer which is provided on at least one side of the laminated separator,   a standard deviation of an IR peak intensity ratio on a surface of the laminated separator which surface is located on the at least one side on which the particle layer is provided being not more than 0.025, the IR peak intensity ratio being calculated from the following formula.
   IR peak intensity ratio=peak intensity which is of a resin contained in the particle layer and which is in an infrared absorption spectrum/peak intensity which is of a resin contained in the heat-resistant layer and which is in an infrared absorption spectrum. 
   
     
     
         2 . The laminated separator of  claim 1 , wherein a weight per unit area of the particle layer on one side of the laminated separator is not less than 0.01 g/m 2  and less than 0.2 g/m 2 . 
     
     
         3 . The laminated separator of  claim 1 , wherein the heat-resistant layer contains an aromatic resin. 
     
     
         4 . The laminated separator of  claim 3 , wherein the aromatic resin is an aramid resin. 
     
     
         5 . A material for a nonaqueous electrolyte secondary battery, comprising a positive electrode, a laminated separator recited in  claim 1 , and a negative electrode which are formed in this order. 
     
     
         6 . A nonaqueous electrolyte secondary battery comprising a laminated separator recited in  claim 1 .